Illuminated writing tablet having concealable illuminating means



H. c. LIEB April 28, 1959 iLLUMINATED WRITING TABLET HAVING CONCEALABLE ILLUMINATING MEANS Filed- Dec. 50. 1955 INVENTOR BY W @04 mmmsmg United States Patent ILLUMINATED TABLET HAVING CON- CEALABLE ILLUMINATIN G MEANS Harry C. Lieb, Rockvllle Centre, N.Y. Application December 30, 1955, Serial No. 556,588 1 Claim. (Cl. 35-62) This invention relates to an illuminated writing tablet designed and constructed so that it may be readily written upon and read in darkness, without chancing that stray illumination will reveal the presence of the person using the tablet.

The principal object of this invention is to provide a writing tablet for use by reconnaissance scouts and the like that is so constructed that in complete darkness items of intelligence may be readily entered upon the tablet, in correct position and spacing, and later may be read from the tablet without revealing the presence of the person using the tablet through stray illumination.

A further object of the invention is to provide a writing tablet of the kind described above which may be written upon and read underwater, and which is therefore useful in recording on-the-spot data observed during underwater explorations, particularly where the data must be recorded, and later read, in darkness.

The construction of the writing tablet which achieves these objectives comprises a transparent writing board on which data may be inscribed with an opaque material, and an illuminating element which is arranged to slidably underlie the writing board so that it may be positioned selectively to illuminate small areas of the writing board. The illuminating element is substantially smaller in area than the writing board and may thus be easily shielded when in use to prevent stray illumination which might reveal the presence of one using the tablet. The construction of I the tablet also comprises means for shielding the entire illuminating element when it is not in use, the arrangement being such that the illuminating element readily and quickly can be moved between its shielded position and those in which it serves to illuminate the areas of the writing board on which data is being inscribed or read. The nature of the illuminating element and the writing surface are such that the tablet may be used underwaterto full advantage.

The following description of one form of a writing tablet incorporating the present invention will serve to exemplify the invention, as well as its objects and advantages.

In the accompanying drawing:

Figure 1 is a top plan view, of one form of a writing tablet incorporating the present invention;

Figure 2 is a side elevational view of the same tablet; and

Figure 3 is a longitudinal sectional view of the same tablet along the lines 3-3 of Figure 1.

The tablet comprises two sheets 10, 12 of similar dimensions which are held in spaced relationship by being afiixed to the transversely extending spacing members 14, 16 which are interposed between the sheets at their upper and lower ends, respectively. This may be seen best in Figures 2 and 3.

In the form of writing tablet illustrated, sheet serves as the writing board and, consequently, this sheet is formed from a transparent material such as Lucite, or some similar shock-resistant plastic. The outer surface of the sheet 10 is etched, or otherwise treated, so that it may be readily inscribed upon by crayon and like materials. If desired, the sheet 10 may be permanently inscribed with spaced titles, such as Azimuth, Distance, Description of Obstacle, etc., so that information concerning these particular titles may be entered in the spaces beneath them.

An illuminating element 18 is slidably mounted between the sheets 10, 12. This element comprises end members 20, 22, of similar construction. The end members comprise a strip 24 terminating at either end in upstanding flanges 26, 28, which give the members a generally U-shaped cross-section. An end member of this kind is slidably positioned on each side margin of the unit consisting of the spaced-apart sheets 10, 12 so that the distal ends of the upstanding flanges of each member overlie respectively, a side margin of the outer face of the sheets 10, 12. This may be seen best in Figures 1 and 3.

An illuminating strip 30 extends transversely and intermediately of the sheets 10, 12 and is fixed at either end, respectively, to the strips 24 of the members 20, 22. The members 20, 22 are thus joined to the illuminating strip 30 to provide an illuminating element 18 which may be slid as a unit along the length of the tablet. It may be seen by reference to Figure 1 that the area of the illuminating strip 30 is relatively small compared with the area of the writing board 10, and that the strip will illuminate only a small section of the board at one time. This area may be easily shielded by the hand or body of the one using the tablet.

One end of the writing board 10 is provided with an opaque area 32, behind which the illuminating element may be positioned when it is not being used. Thus, stray illumination from the strip will not disclose the presence of the one using the tablet. However, the arrangement is such that a selected portion of the writing board can be quickly illuminated when it is desired to use the board. It will be appreciated that the opaque section 32 may be provided by an opaque coating material or by simply aflixing a strip of opaque material to the board 10.

The desired illumination on the strip 30 may be pro vided by a phosphor coating which is radioactivated or stimulated prior to use by exposure to light. For example, a zinc sulphide phosphor coating may be used and this may be activated by the addition thereto of B-emitting strontium isotopes, or by exposure to light prior to use.

It will be understood that the opaque shielding area 32 may be positioned at either end of the tablet, or at a space along its length, and that the sheet 12 may also serve as a writing board if transparent and provided with a similar shielding area. In this event both sides of the illuminating strip 30 would be provided with the required illuminating coating. The writing tablet may also be provided with fastening devices such as the snap buttons 34 by means of which the tablet may be fixed to the clothing of user in position where it may be readily reached for use.

Having thus described the invention what is claimed as new is:

A writing tablet comprising two sheets fixedly spaced apart in parallelism, at least one of said sheets being transparent over the majority of its area, the remainder of its area being opaque and extending across its sheet, a phosphorescent illuminating element interposed between said sheets and mounted for sliding movement with respect to said sheets to illuminate successive portions Patented Apr. 28, 1959 thereof, said illuminating element having an area no larger than that of said opaque area, whereby said i1- luminating element may be slidably positioned behind said opaque area to shield the illumination emitted therefrom, and U-shaped end members secured to the ends of the illuminating element and extending around the side edges of both sheets and contacting a portion of each edge face of each sheet to facilitate sliding movement of the element.

References Cited in the tile of this patent UNITED STATES PATENTS Petrie Ian. 4, 1916 Willis Sept. 7, 1920 Willis Apr. 5, 1921 Hartmann Apr. 30, 1940 Rosenblum Oct. 19, 1948 Blumberg Apr. 27, 1954 

